In many types of pleasure boats, an outboard is connected to a boat transom by clamps. Such motors are vulnerable to theft since they are often left unattended for long periods of time. Additionally, it is possible for the clamps to become loose due to motor vibration or other conditions, which can result in less than optimum transmission of power from the motor to the boat, damage to the motor or boat, or in extreme conditions loss of the motor.
In U.S. Pat. No. 3,696,371, an outboard motor alarm system is disclosed which will result in an alarm sounding if a thief loosens the clamps holding the motor to the transom, or if the clamps are loosened a sufficient amount during use will indicate such looseness. However the system as described in said patent is difficult to install in a boat since the alarm system and power supply are remote from the boat motor clamps, which requires cabling; or in an alternative embodiment a transmitter must be located adjacent the outboard motor, and a receiver adjacent an alarm and power supply remote from the motor.
According to the present invention, an alarm system for a boat outboard motor connected to a boat transom by clamps is provided which positively indicates if theft is attempted, and also senses loosening of the motor, yet may be easily, quickly, simply, and reliably retrofit to an existing boat. According to the present invention there is provided a self-contained alarm system which includes a housing containing a power source and a signalling means, and housing preventing access to the power source and the signalling means. The housing includes contact means for engaging a clamp which connects the motor to the boat transom so that when the clamp is engaged thereby the power source does not actuate the signalling means. However when the contact means is not engaged by a clamp, the power source actuates the signalling means, powered by the power source.
A wide variety of options are available for the details of the interconnection between the housing and the motor clamps. For example in one embodiment the housing includes first and second arms, each with an electrically conductive sensor member mechanically connectable to one of the clamps of the outboard motor. If either of the clamps is mechanically backed off from the electrically conductive sensor member, the electrical resistance between the clamp and the respective sensor increases, causing an "open circuit" type of condition and activating the signalling means through circuitry means also located within the housing. In another embodiment, only one of the clamps is in operative communication with electrically conductive means, bridging a pair of electrical connectors which are operatively connected to the circuitry, signalling, and power device within the housing. In yet another embodiment, the clamp engages a spring pressed plunger so that when the clamp is tight a movable contact bridging a pair of stationary contacts is open, and closes when the clamp is loosened, causing the spring to move the movable bridging contact to its closed position bridging the stationary contacts. In this latter embodiment circuitry means are not necessary.
In both of the last described embodiments, dual sensing structures can be provided so that both the clamps are operatively associated with contacts so that loosening of either of the clamps sounds an alarm, flashes lights, or produces another type of signalling. Also, it the latter two embodiments only a single arm need be provided associated with the housing, and if desired a hub of the housing can be connected to the transom.
It is the primary object of the present invention to provide an easily retrofit self-contained signalling system for a boat outboard motor with all components self-contained, and which is easily retrofit onto existing boats. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.